Gas turbine engines, such as those utilized in commercial aircraft, frequently utilize a geared turbofan engine. In a typical geared turbofan engine, a forward fan is connected to a central shaft via a gearing system. The gearing system allows multiple components of the turbine engine to be rotated at different speeds off of the same shaft.
One type of commonly used gear system is referred to as an epicyclic gear system. An epicyclic gear system has one or more outer gears (intermediate gears), revolving about a central gear (sun gear). Typically, the intermediate gears are mounted on a carrier which itself may rotate relative to the sun gear. Epicyclic gear systems also typically incorporate the use of an outer ring gear, which meshes with the intermediate gears.
In one example, the carrier is fixed from rotation about the sun gear and this is referred to as a Star system. The intermediate gears are referred to as star gears and rotate about a fixed axis in the carrier and cause the ring gear to rotate in the opposite direction as the sun gear.
In another example, the ring gear is fixed and the carrier and intermediate gears are allowed to rotate about the sun gear. This type of gear system is referred to as a Planetary system. The intermediate gears are referred to as planet gears. In this example the carrier rotates in the same direction as the sun gear.
During operation of the planetary gear system a lubricant/coolant fluid, such as oil is provided to the internal components of the planetary gear system. The lubricant/cooling fluid cools the components and prevents wear/seizing of the gear system.